Any large-scale Italian map will reveal a number of places with double-barrelled names ending in "Scalo". Do not go there, or if you must, don't stop. In its original maritime sense, the word meant a port of call. When the railways were built it was adopted to signify an isolated station serving a rural area, often situated miles from the locality it was named after. The straggling, soulless blots on the landscape that grew up around those stations, now largely disused, are as depressed and depressing as any whistle-stop town in the American midwest.

Ischiano Scalo, where this book is set, is the epitome of such places. Eurostar expresses speeding between Genoa and Rome sweep past every hour, but only two snail trains a day stop. It is also just off the Via Aurelia, the main coastal highway, and in the formerly malarial Maremma swamplands, the grungiest corner of trendy Tuscany. Not only is there no "there" there, but the unremitting current of traffic passing through is a constant and painful reminder to the inhabitants that life is elsewhere.

But if by now you're thinking that you don't want to read about such a place, never mind go there, you'd be making a big mistake, because in Niccolo Ammaniti's hands Ischiano Scalo turns out to be the Italian equivalent of Little Britain. His earlier novel, I'm Not Scared, was a haunting, atmospheric thriller with the poise and restraint of postwar neo-realist films. It was also an international bestseller, and perhaps buoyed by that success Ammaniti has allowed himself to indulge in this seductive black farce set in a sensationally dysfunctional community, which reveals that he is not only a master storyteller but has a very nice line in sly humour as well. He is quite clearly enjoying himself - you can almost see the smile on his lips as he gleefully teases out the various narrative possibilities - and that enjoyment is infectious.

The novel is richly textured and populated with memorable characters, but there are two principal and eventually convergent plot lines. One centres on Graziano Biglia, a rapidly ageing Latin lover with an equine member, the brains of a quail and a heart of gilt, who has decided that the time has finally come to give up his vagabond existence, marry the 21-year-old nude dancer he met in a nightclub last summer, settle down in his native village and get rich by opening a shop selling brand-name luxury leisureware. The other concerns Pietro Moroni, the sensitive younger son of a violently alcoholic farmer and his beaten-up, beaten-down and over-medicated wife. Pietro is the surrogate brother and secret lover of the classiest and most beautiful girl at his school, but also a loner and a born victim who can easily be bullied by the local chavs into becoming the fall guy for their criminal schemes.

To reveal the resulting cascade of events would be equally criminal. Suffice it to say that everyone's daft and devious decisions, which seemed a good idea at the time, go horribly wrong in a manner as unpredictable as the dark comedy of life itself. Ammaniti cunningly lulls us into a state of amused complicity with a succession of scenes that are often laugh-out-loud funny, only to turn the screw with almost sadistic pleasure in the last pages, when the least likely perpetrator gratuitously murders the least likely victim, all laughs abruptly cease and the book ends on a note of disturbing irresolution. This final twist may feel a little forced to some readers, but there is no question that it is brutally effective and deeply shocking.

Steal You Away may not be an indisputable classic like I'm Not Scared, but it is a compelling and entertaining narrative which is very well served by Jonathan Hunt's stylish translation. I do, however, fear for the author's reputation in his own country. Ammaniti has long been viewed askance by some members of the Italian cultural politburo as an arrogant, independent over-achiever who neither needs nor intends to be beholden to any of them, thank you. His latest offering, however, delivers a series of punishing blows below the belt to the bella figura-obsessed Italian public itself. The combination of hilarious cameos and caustic authorial asides mercilessly mocks every stereotype in the smug national self-image, from middle-aged but still studly Romeos capable of pulling 300 women in a single season at the beach, to sturdy Tuscan peasants who are at one with nature and glow with inner wisdom - not to mention those plucky, indestructible mammas who may be poor but still have their pride and make the best fettucine in the world. Forget everything I said earlier. Forget Lucca, Siena and Cortona too. You'd be crazy not to visit Ischiano Scalo.

· Michael Dibdin's Back to Bologna is published by Faber. To order Steal You Away for £11.99 with free UK p&p call Guardian book service on 0870 836 0875.